The present invention relates to a new and distinct variety of mushroom plant of Agaricus subrufescens Peck. The present plant is an edible mushroom.
Agaricus subrufescens was first described in 1893 by C. H. Peck, the New York State Botanist, from mushrooms being cultivated in a greenhouse in Dosoris, N.Y., and some additional specimens found growing in the woods nearby. The mushroom, nicknamed the ‘almond mushroom’ due to its fragrance and taste, was widely cultivated, sold, and eaten in the Atlantic states of the United States of America from at least Massachusetts to Washington, D.C. in the latter years of the 19th century. Spawn (i.e., inoculum culture for farming) of Agaricus subrufescens was even offered for sale in catalogs of the day. Subsequently, commercial production of Agaricus subrufescens declined as market trends changed, and by the 1920-1930 period, virtually the only mushroom species being cultivated in the United States was the related ‘button mushroom’ species, Agaricus bisporus (Lange) Imbach. Agaricus subrufescens mushrooms have occasionally been found growing wild outside of northeastern North America in place such as, for example, California, Israel, and Hawaii. The recently described mushroom Agaricus rufotegulis Nauta from the Europe is, based on ITS1+2 and other DNA sequences, actually Agaricus subrufescens, and the same is true of the mushroom Agaricus brasiliensis Wasser et al. from South America.
The history of the mushroom Agaricus subrufescens, as well as a discussion of its properties as an easily cultivated mushroom has been reviewed and present by Kerrigan, one of the inventors of record, in several different articles circa 1983-1984. A culture of Agaricus subrufescens was isolated by Kerrigan from soil in California in 1982 and was subsequently sold commercially to hobbyist mushroom growers. Reproductive mode(s) and genetic behavior of this strain were investigated by Kerrigan and Ross (1987), and Kerrigan (2005).
Agaricus subrufescens mushrooms have more recently begun to be cultivated again on a wide scale, particularly in Brazil and Japan, as a ‘medicinal mushroom’ that is marketed primarily in Japan. However, in this context, the mushroom is typically referred to (incorrectly) as (1) Agaricus blazei Murr., (2) Agaricus blazei Marr. sensu Heineman, (3) Agaricus sylvaticus, or the recently coined (4) Agaricus brasiliensis. However, the data presented below and in Kerrigan, “Agaricus subrufescens, a cultivated edible and medicinal mushroom, and its synonyms,” Mycologia, 97(1), May 18, 2005, pp. 12-24, the disclosure of which is incorporated herein by reference, indicate that the medicinal mushroom from Brazil and Japan is biologically and phylogenetically the same species as Agaricus subrufescens from North America. As Peck's species name Agaricus subrufescens is older than either Argaricus brasilensis or Agaricus rufotegulis, it has a nomenclatural priority under the International Code of Botanical Nomenclature and is therefore the correct name of the species. Therefore, the name Agaricus subrufescens is used herein inclusively. The species name applies not only to phylogenetically congruent isolates and specimens from all parts of the world but also to hybrids between them.
Cultivated material of Agaricus subrufescens was obtained from California, Brazil, Japan, and China. Hybridization (crossing) experiments were performed on selected pairs of stocks. When single-spore isolates (SSIs) from two different stocks are successfully crossed, the resulting hybrid incorporates genetic material from both progenitors, and the traits inherited from the parents may exist in a novel combination, or be intermediate in their nature. The successful production of hybrids strongly supports treatment of the parental isolates as members of a single species, regardless of their origin.
Furthermore, rDNA ITS1+2 sequences from many strains of Agaricus subrufescens were obtained from North America, South America, Europe, and Hawaii. It has been observed that Agaricus subrufescens has a considerable degree of cultural and morphological variability, but this variability is not vastly greater than in other species of Agaricus including Agaricus bisporus. It has also been found that the DNA sequences of diverse Agaricus subrufescens cultures are either identical or extremely similar, as is typically the case within other species of Agaricus, and share characteristics polymorphisms not known from other species. Thus, molecular markers have been developed that identify the species, identify strains within the species, and document the transmission of hereditary material from parental strains into offspring.